Supporting Dynamic Multipoint Communication Configuration

ABSTRACT

An apparatus, method and computer program product for supporting dynamic multipoint communication configuration stations include defining at least two different communication transmission sets for cellular-based communication between base station and terminal, wherein the communication transmission sets are related to a downlink reference signal configuration; and assigning a communication transmission set for use in a current transmission related to the cellular-based communication.

FIELD OF THE INVENTION

The present invention relates to an apparatus, method and computerprogram product for supporting dynamic multipoint communicationconfiguration stations. In particular, the present invention relates toan apparatus, method and computer program product for supporting dynamicmultipoint communication configuration in evolved Node Bs and userequipment.

RELATED BACKGROUND ART

Prior art which is related to this technical field can e.g. be found bythe technical specifications of the 3GPP 36 series standard. Particularreference is made to TS 36.814 (current version: 9.0.0) of the 3GPP.

The following meanings for the abbreviations used in this specificationapply:

-   3G: 3^(rd) Generation-   3GPP: 3^(rd) Generation Partnership Project-   CoMP: Coordinated Multi-Point Transmission-   CRS: Common Reference Symbols-   CSI-RS: Channel State Information Reference Symbols-   CQI: Channel Quality Indicator-   DCI: Downlink Control information-   DL: Downlink-   DM RS: Demodulation Reference Symbols-   DRS: Dedicated (UE-Specific) Reference Symbols-   eNB: evolved Node B (base station)-   ID: Identifier-   LTE: Long Term Evolution-   LTE-A: Long Term Evolution Advanced-   PDCCH: Physical Downlink Control Channel-   PDSCH: Physical Downlink Shared Channel-   PMI: Precoding Matrix Indicator-   RI: Rank Indicator-   RRC: Radio Resource Control-   RS: Reference Signal-   TM: Transmission Mode-   TX: Transmit (ter)-   UE: User Equipment

Recently, in LTE-Advanced related standardization meetings it is underdiscussion whether data transmission from multiple cells towards oneuser should be supported. Such data transmission from multiple cellstowards one user is also called Coordinated Multipoint Transmission(CoMP).

Since the present discussion merely focuses on rather general aspects,there is a need for detail solutions related to the technicalimplementation.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide suchdetail solution which in the present case is related to supportingdynamic multipoint communication configuration.

According to a first aspect of the present invention, this isaccomplished by an apparatus, comprising communication configurationmeans configured to define at least two different communicationtransmission sets for cellular-based communication between base stationand terminal, wherein the communication transmission sets are related toa downlink reference signal configuration; and communicationtransmission set switching means configured to assign a communicationtransmission set for use in a current transmission related to thecellular-based communication.

Modifications of the first aspect may be as follows.

The apparatus according to the first aspect may be configured to besuitable for supporting dynamic multipoint communication configurationstations.

Further, a first communication transmission set can correspond to asingle cell transmission and a second communication transmission set cancorrespond to a transmission involving two neighboring cells withoverlapping coverage area forming a serving sector and a neighboringsector.

The two neighboring cells with overlapping coverage area can each beserved by the same base station.

The second communication transmission set can comprise informationselected from the group comprising a vertical shift in the commonreference signal patterns between the neighboring cells, the identitiesof the neighboring cells and a transmission sequence of the neighboringcells.

The second communication transmission set can include information totrigger the terminal using an operation mode in which antenna ports ofthe neighboring sector are considered virtual antenna portsconsecutively adding to the antenna ports of the serving sector.

A definition of a communication transmission set can relate to radioresource control signaling.

The communication transmission set switching means can be configured toassign a communication transmission set based on downlink assignmentsignaling related to the current transmission.

According to a second aspect of the present invention, the object isaccomplished by an apparatus, comprising a communication configurationprocessor configured to define at least two different communicationtransmission sets for cellular-based communication between base stationand terminal, wherein the communication transmission sets are related toa downlink reference signal configuration; and a communicationtransmission set switching processor configured to assign acommunication transmission set for use in a current transmission relatedto the cellular-based communication.

Modifications of the second aspect of the present invention maycorrespond to the modifications of the first aspect.

According to a third aspect of the present invention, the object isaccomplished by an evolved Node B and User Equipment, respectively,comprising an apparatus according to the first or second aspect of thepresent invention or any one of their modifications, wherein the userequipment further comprises an information sharing processor configuredto initiate sharing the communication transmission sets with an evolvedNode B serving the User Equipment, and the evolved Node B furthercomprises an information sharing processor configured to initiatesharing the communication transmission sets with a User Equipment servedby the evolved Node B.

According to a fourth aspect of the present invention, the object isaccomplished by a method, comprising defining at least two differentcommunication transmission sets for cellular-based communication betweenbase station and terminal, wherein the communication transmission setsare related to a downlink reference signal configuration; and assigninga communication transmission set for use in a current transmissionrelated to the cellular-based communication.

Modifications of the fourth aspect may be as follows.

The method according to the fourth aspect may be configured to besuitable for supporting dynamic multipoint communication configurationstations.

Further, a first communication transmission set can correspond to asingle cell transmission and a second communication transmission set cancorrespond to a transmission involving two neighboring cells withoverlapping coverage area forming a serving sector and a neighboringsector.

The two neighboring cells with overlapping coverage area can each beserved by the same base station.

The second communication transmission set can comprise informationselected from the group comprising a vertical shift in the commonreference signal patterns between the neighboring cells, the identitiesof the neighboring cells and a transmission sequence of the neighboringcells.

The second communication transmission set can include information totrigger the terminal using an operation mode in which antenna ports ofthe neighboring sector are considered virtual antenna portsconsecutively adding to the antenna ports of the serving sector.

The defining a communication transmission set can relate to radioresource control signaling.

The assigning a communication transmission set can include downlinkassignment signaling related to the current transmission.

The method according to the fourth aspect or any of its modificationsmay be performed by the apparatus according to the first or secondaspect or suitable ones of their modifications.

According to a fifth aspect of the present invention, the object isaccomplished by a computer program product comprisingcomputer-executable components which perform, when the program is run ona computer, defining at least two different communication transmissionsets for cellular-based communication between base station and terminal,wherein the communication transmission sets are related to a downlinkreference signal configuration; and assigning a communicationtransmission set for use in a current transmission related to thecellular-based communication.

Modifications of the fifth aspect may be as follows.

The computer program product according to the fifth aspect may besuitable for supporting dynamic multipoint communication configurationstations.

The computer program product according to the fifth aspect may beembodied as a computer-readable storage medium.

Otherwise, modifications of the fifth aspect may correspond to themodifications of the fourth aspect.

It is to be understood that any of the above modifications can beapplied singly or in combination to the respective aspects to which theyrefer, unless they are explicitly stated as excluding alternatives.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, details and advantages willbecome more fully apparent from the following detailed description ofthe preferred embodiments which is to be taken in conjunction with theappended drawings, in which:

FIG. 1 shows an apparatus according to certain embodiments of thepresent invention;

FIG. 2 shows a flow chart illustrating a method according to certainembodiments of the present invention;

FIG. 3 shows an example for the CRS collision issue in CoMPtransmission;

FIG. 4 illustrates a simple intra-site CoMP operation between twoco-located cells, two antennas each; and

FIG. 5 illustrates an example in which a user equipment treats antennaports from another sector as virtual antenna ports in accordance withcertain embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, description is made to what are presently consideredto be preferred embodiments of the present invention. It is to beunderstood, however, that the description is given by way of exampleonly, and that the described embodiments are by no means to beunderstood as limiting the present invention thereto.

For example, for illustration purposes, in some of the followingexemplary embodiments, supporting dynamic multipoint communicationconfiguration in the context of LTE-Advanced is described in order toillustrate a solution to the needs of the 3GPP. However, it should beappreciated that these exemplary embodiments are not limited for useamong this particular type of wireless communication system, andaccording to further exemplary embodiments, the present invention can beapplied also to other types of cellular-based communication systems andaccess networks in which the feature of multipoint communication can bepresent.

Though, certain embodiments of the present invention relate to 3GPPLTE-Advanced. In more detail, certain embodiments of the presentinvention are related to the configuration of an LTE-Advanced eNB andcomponents thereof as well as of an LTE-Advanced UE and componentsthereof, or the like.

However, as indicated above, the present invention is not limited to eNBand UE, but other embodiments of the present invention are related togeneral base station nodes and terminal nodes, respectively, andcomponents thereof.

FIG. 1 shows a principle configuration of an example for an apparatusaccording to certain embodiments of the present invention. One optionfor implementing this example for an apparatus according to certainembodiments of the present invention would be a component in an evolvedNode B according to LTE-Advanced, while another option for implementingthis example would be a component in a user equipment according toLTE-Advanced.

Specifically, as shown in FIG. 1, the example for an apparatus comprisesa communication configuration processor (11) configured to define atleast two different communication transmission sets for cellular-basedcommunication between base station and terminal, wherein thecommunication transmission sets are related to a downlink referencesignal configuration; and a communication transmission set switchingprocessor (12) configured to assign a communication transmission set foruse in a current transmission related to the cellular-basedcommunication.

FIG. 2 shows a principle flowchart of an example for a method accordingto certain embodiments of the present invention. That is, as shown inFIG. 2, this method comprises defining (S1) at least two differentcommunication transmission sets for cellular-based communication betweenbase station and terminal, wherein the communication transmission setsare related to a downlink reference signal configuration; and assigning(S2) a communication transmission set for use in a current transmissionrelated to the cellular-based communication.

One option for performing the example of a method according to certainembodiments of the present invention would be to use the apparatus asdescribed above or a modification thereof which becomes apparent fromthe embodiments as described herein below.

According to certain embodiments of the present invention, a CoMP isenabled which allows a very fast communication (practically involvingzero-delay) between the cooperating eNBs. Specifically, according to thesignaling mechanisms of certain embodiments of the present invention asimple CoMP implementation for initial CoMP deployments is enabledwithout a need for high backhaul capacity with low latency. Moreover,according to certain embodiments of the present invention animplementation example is provided for the transmission of PDSCH frommultiple cells in which data symbols are punctured to provide space forthe common reference signal. Namely, when multi-cell transmission isenabled the number of reference signal positions that needs puncturingcould change, for which no solution is known in the prior art.

FIG. 3 illustrates an example of such RS collision issue showing thesequence of symbols of subcarriers. If UE is performing CoMP and bothsectors 1 and 2 are transmitting data to it, normally there is somevertical shift between the CRS patterns of neighbor sectors so that theUE has to do rate-matching or puncturing on the resource elementsoccupied by CRS from both sectors.

According to the specification TR 36.814 of the 3GPP an approach to thisissue is considering to have transmission cells configuredsemi-statically.

However, as there are many different aspects to be taken into accountwhen deciding for the scheduling of the UEs, a UE configured formulti-cell transmission might not always be transmitted to from multiplecells. With semi-static configuration this would lead to an increasedoverhead, since the UE, when transmitted to only from single cell, wouldstill puncture the common reference signal positions from other cells.

Hence, according to certain embodiments of the present invention, in thesimple CoMP case where coordination takes place between the two cells(sectors) of a single eNB (see FIG. 4), the UE on the border area of thetwo cells can benefit from the CoMP transmission from all the fourantennas of the two cells (two antennas per cell, indicated by 2-TX).

Specifically, according to certain embodiments of the present invention,to support dynamic switching between single and multi-cell transmission,one or more of the following options may be implemented.

Two or more higher layer (e.g. RRC signaling) configurations aredefined, where each configuration corresponds to a relevant semi-staticconfiguration of the transmission set. For example, configuration 0 maycorrespond to single cell transmission (as defined in 3GPP Release 10),and configuration 1 would mean a two sector transmission, i.e. a servingsector and one neighboring sector. In the latter case, the neighboringsector's information like CRS vertical shift, the transmission sequence,the cell-id, etc. are included in the configuration and is sharedbetween eNB and UE.

A signaling in the DL assignment by e.g. using DCI can be used to switchbetween the configurations. Such signaling could be established byreinterpretation of the existing DL assignment fields or by adding newbits. Also a new type of DL assignment can be defined for this purpose.The DL assignment may be present in only the UE-specific PDCCH searchspace or also in the common search space. Depending on the signaling theUE can correctly interpret e.g. the PMI field in the DCI e.g. using 2-TXor 4-TX codebook.

In the case a dual-sector transmission is indicated with the DLassignment, the UE can consider the antenna ports from neighbor sectorsas “virtual antenna ports”, which are perhaps associated with differentCRS/CSI-RS locations, etc. As illustrated in FIG. 5, UE takes theantenna ports 1&2 from the neighboring cell as virtual antenna ports andtreats them as antenna ports 3&4 (by consecutive adding to the antennaports of the serving cell/sector) in the demodulation or in the CSTmeasurements. This allows for the eNB to use e.g. existing 4-TX antennacodebook and related procedures when deriving the CSI feedback for theCoMP operation.

The configurations could include details related to a reference signalconfiguration as follows:

In a DRS based transmission, DM RS sequences could be different betweendifferent configurations. The signaling in the DL assignment could thenbe combined with other DRS configuration related signaling in the DLassignment to derive the DM RS sequence.

In a CRS based transmission, multi-cell transmission based on CRS couldbe envisioned. As an example, UE could be configured with 4TX assignmentand in case of single cell transmission the DL assignment isreinterpreted by the UE as 2TX. On the other hand, if dual celltransmission is indicated, 4TX demodulation is used (while othercombinations are also. Possible). In this case, the UE needs all theinformation related to a configuration of the CRS in adjacent cell(power offsets, PCI, etc.) so that it can derive proper channelestimates. Moreover, UE could always use CSI-RS to derive the feedback(CQI, PMI, RI, single/dual cell) as the adjacent cell's CRS could bebadly interfered from PDSCH transmission in its own cell.

According to certain embodiments of the present invention, specificimplementation examples could be established as described below:

Considering a case where each sector has two TX antenna ports and twotransmission sets have been configured for the UE (for illustrationpurposes, reference is again made to FIG. 5:

-   -   Config.0 corresponds to single sector transmission (where sector        1 is the serving sector of the UE).    -   Config.1 corresponds to dual-sector transmission (including        sector 1 and sector 2), and all the relevant information on the        reference signals of sector 2 are included.

When the UE is configured in a DRS based TX mode, e.g. Transmission Mode9, the corresponding DCI format has e.g. 1 bit (explicitly orimplicitly) indicating which configuration is used for current DLassignment. If it indicates Config.0, then UE follows single cell 2TXtransmission. If it indicates dual-cell transmission, the UE assumesthere are four TX antenna ports for the transmission and up to fourlayers can be transmitted. In this case the UE does rate-matching of thereceived data around the CRS locations for both sector 1 and sector 2.

When the UE is configured in CRS based TX mode, the corresponding DCIformat may still have 1 bit to indicate which configuration is to beused. If the DL assignment indicates config.1, the UE knows 4TXtransmission is applied, and it considers antennas from the neighborsector as virtual antenna ports and takes into account the correspondingCRS locations.

Thus, as is apparent from the above description of the preferredembodiments of the present invention, certain embodiments can achievethe following advantages:

DL CoMP can be introduced into LTE Release 11 in a most simple way.Further, it is possible to re-use LTE Release 8 codebooks andtransmission schemes to a large extent (both open loop and closed loop).Still further, the proposed dynamic switching between single andmulti-cell transmission makes it easier to harvest gains for the CoMPusers. Eventually, the system impact (both related to standardizationand implementation) is minimized, making a cost-effective introductionof the above features feasible.

According to the above description, it should thus be apparent thatexemplary embodiments of the present invention provide, for example fromthe perspective of a network element such as an evolved Node B (eNB) anda user equipment, respectively, or a component thereof, an apparatusembodying the same, a method for controlling and/or operating the same,and computer program(s) controlling and/or operating the same as well asmediums carrying such computer program(s) and forming computer programproduct(s).

For example, described above are apparatuses, methods and computerprogram products capable of supporting dynamic multipoint communicationconfiguration.

Implementations of any of the above described blocks, apparatuses,systems, techniques or methods include, as non limiting examples,implementations as hardware, software, for example in connection with adigital signal processor, firmware, special purpose circuits or logic,general purpose hardware or controller or other computing devices, orsome combination thereof.

What is described above is what is presently considered to be preferredembodiments of the present invention. However, as is apparent to theskilled reader, these are provided for illustrative purposes only andare in no way intended that the present invention is restricted thereto.Rather, it is the intention that all variations and modifications beincluded which fall within the spirit and scope of the appended claims.

1. An apparatus, comprising: communication configuration meansconfigured to define at least two different communication transmissionsets for cellular-based communication between base station and terminal,wherein the communication transmission sets are related to a downlinkreference signal configuration; and communication transmission setswitching means configured to assign a communication transmission setfor use in a current transmission related to the cellular-basedcommunication.
 2. The apparatus according to claim 1, wherein a firstcommunication transmission set corresponds to a single cell transmissionand a second communication transmission set corresponds to atransmission involving two neighboring cells with overlapping coveragearea forming a serving sector and a neighboring sector.
 3. The apparatusaccording to claim 2, wherein the two neighboring cells with overlappingcoverage area are each served by the same base station.
 4. The apparatusaccording to claim 2, wherein the second communication transmission setcomprises information selected from the group comprising a verticalshift in the common reference signal patterns between the neighboringcells, the identities of the neighboring cells and a transmissionsequence of the neighboring cells.
 5. The apparatus according to claim2, wherein the second communication transmission set includesinformation to trigger the terminal using an operation mode in whichantenna ports of the neighboring sector are considered virtual antennaports consecutively adding to the antenna ports of the serving sector.6. The apparatus according to claim 1, wherein a definition of acommunication transmission set relates to radio resource controlsignaling.
 7. The apparatus according to claim 1, wherein thecommunication transmission set switching means is configured to assign acommunication transmission set based on downlink assignment signalingrelated to the current transmission.
 8. A User Equipment, comprising: anapparatus according to claim 1; and information sharing means configuredto initiate sharing the communication transmission sets with an evolvedNode B serving the User Equipment.
 9. An evolved Node B, comprising: anapparatus according to claim 1; and information sharing means configuredto initiate sharing the communication transmission sets with a UserEquipment served by the evolved Node B.
 10. A method, comprising:defining at least two different communication transmission sets forcellular-based communication between base station and terminal, whereinthe communication transmission sets are related to a downlink referencesignal configuration; and assigning a communication transmission set foruse in a current transmission related to the cellular-basedcommunication.
 11. The method according to claim 10, wherein a firstcommunication transmission set corresponds to a single cell transmissionand a second communication transmission set corresponds to atransmission involving two neighboring cells with overlapping coveragearea forming a serving sector and a neighboring sector.
 12. The methodaccording to claim 11, wherein the two neighboring cells withoverlapping coverage area are each served by the same base station. 13.The method according to claim 11, wherein the second communicationtransmission set comprises information selected from the groupcomprising a vertical shift in the common reference signal patternsbetween the neighboring cells, the identities of the neighboring cellsand a transmission sequence of the neighboring cells.
 14. The methodaccording to claim 11, wherein the second communication transmission setincludes information to trigger the terminal using an operation mode inwhich antenna ports of the neighboring sector are considered virtualantenna ports consecutively adding to the antenna ports of the servingsector.
 15. The method according to claim 10, wherein defining acommunication transmission set relates to radio resource controlsignaling.
 16. The method according to claim 10, wherein assigning acommunication transmission set includes downlink assignment signalingrelated to the current transmission.
 17. A computer program productcomprising computer-executable components which perform, when theprogram is run on a computer: defining at least two differentcommunication transmission sets for cellular-based communication betweenbase station and terminal, wherein the communication transmission setsare related to a downlink reference signal configuration; and assigninga communication transmission set for use in a current transmissionrelated to the cellular-based communication.
 18. The computer programproduct according to claim 17, embodied as a computer-readable storagemedium.